This invention relates to brick veneer/cavity wall construction and, more particularly, to a device used in association with window and door installations in a veneer/cavity wall system to provide for proper water dissipation and moisture drainage.
Walls systems having a masonry exterior are typically constructed of at least one vertical layer of masonry and at least a second vertical layer of a material forming a back-up system. The back-up system may be constructed of lumber or of a concrete masonry unit. The brick and back-up system are typically bonded together by horizontal metallic ties spaced in a vertical plane. A space is often provided in such wall systems (e.g., cavity wall systems) between the brick and back-up system for moisture drainage. Insulation may also be placed in the space to improve the energy efficiency of masonry buildings.
Masonry offers great durability and appeal. Masonry walls, however, tend to be permeable, allowing water to pass through the wall under certain conditions, such as storms associated with high winds. To solve the water leakage problem, recent construction trends have been towards a masonry wall system where the brick is intentionally separated from the back-up by a small space of from 1-4 inches. When insulation is placed in the space, an effort is made to maintain at least one inch of space between the brick and insulation for drainage.
In masonry construction using brick exteriors, it is critical to provide proper drainage in the form of a clear cavity within the wall system to prevent water related problems. A proper drainage path allows penetrating water to flow unobstructed to areas of the wall which facilitate drainage back to the exterior. This is even more important around openings in the wall for doors and windows to avoid pockets or areas the water may collect and/or drain to undesirable areas.
Masonry walls constructed with a back-up system and intervening drainage space are relatively effective and durable when guidelines are followed and drainage space is maintained. Problems often arise in construction, however, in maintaining an unobstructed space between the brick and associated back-up system. During construction, mortar often falls into the sometimes narrowed drainage space between the brick and back-up or between the brick and insulation, blocking the flow of water out of the wall interior. Additionally, discontinuities in the wall, such as openings for doors and windows, require attention to detail for the tradesman to properly provide for water and moisture handling.
Normally, the 1 to 2 inch air space provided between the brick and back-up system is adequate to provide drainage. However, in addition to mortar entering the air space during the process of brick laying, mortar extruded during the brick-laying process from the outer brick wythe also accumulates in the air space creating blockages, either falling into the air space or simply extending into and blocking the air space. Environmental debris may also fall, or blow, into the air space. Obstructions from these or other sources, either singly or together, may substantially block the flow of water out of portions of the air space. Such blockage is even more problematic in the areas surrounding windows, doors or other interruptions in the cavity wall.
When blockage of water occurs, freezing of accumulated water inside the wall may cause damage to the wall system, window or door. In masonry construction using brick exteriors, for example, it is especially important to avoid water saturation which upon freezing and thawing may lead to cracking, spalling and disintegration of masonry structures. Furthermore, penetrating water can cause efflorescence to appear on exterior surfaces or water can be transferred to the interior of the building causing mold growth, metal supports to corrode, insulation to lose its effectiveness, deterioration of the window/door and interior finishes. When the cavity is dry and air can circulate, the conditions for mold growth are minimized.
Because of the importance of masonry structures in general, a need exists for a better method of ensuring water drainage from within brick walls. Flashing and weeps are recommended by the BIA (Brick Industry Association) on all masonry window and door sill and lintel installations to direct the flow of moisture from the wall cavity and keep the underlying materials dry. Presently, a variety of materials are used such as copper, zinc, lead, stainless steel, polyethylene, polyvinylchloride, etc. Additionally, a variety of weep styles have been used. Examples of known weep systems include a length of sisal rope that is positioned atop the flashing material and in the joint between adjacent bricks at the sill or lintel of the door or window.
Unfortunately, tradesmen and installers frequently fail to install the rope or any other weep device to allow for proper drainage at the sill or lintel. The prior art does not offer an effective and economical solution that is easily and reliably installed around cavity wall windows and doors. To date, there are no known “combination materials” that provide both flashing and weep utility for sills and lintels. Simply stated, there exists a need for a combination of flashing and weep to detail sills and lintels properly to inhibit and avoid water accumulation and ineffective drainage.